1. Field of the Invention
Embodiments of the present invention generally relate to a shadow frame for use in a processing chamber.
2. Description of the Related Art
Modern semiconductor devices require the formation of features, such as OLEDs, transistors, and low-k dielectric films, by depositing and removing multiple layers of conducting, semiconducting and dielectric materials from a glass substrate. Glass substrate processing techniques include plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), etching and the like. Plasma processing is widely used in the production of flat panel devices due to the relatively lower processing temperatures required to deposit a film and good film quality which can result from using plasma processes.
In general, plasma processing involves positioning a substrate on a support member (often referred to as a susceptor or heater) disposed in a vacuum chamber and forming a plasma adjacent to the upper exposed surface of the substrate. The plasma is formed by introducing one or more process gases into the chamber and exciting the gases with an electrical field to cause dissociation of the gases into charged and neutral particles. A plasma may be produced inductively, e.g., using an inductive RF coil, and/or capacitively, e.g., using parallel plate electrodes, or by using microwave energy.
During processing, the edge and backside of the glass substrate as well as the internal chamber components must be protected from deposition. Typically, a deposition masking device, or shadow frame, is placed about the periphery of the substrate to prevent processing gases or plasma from reaching the edge and backside of the substrate and to hold the substrate on a support member during processing. The shadow frame may be positioned in the processing chamber above the support member so that when the support member is moved into a raised processing position, the shadow frame is picked up and contacts an edge portion of the substrate. As a result, the shadow frame covers several millimeters of the periphery of the upper surface of the substrate, thereby preventing edge and backside deposition on the substrate.
With consideration of the benefits of using a shadow frame, there are a number of disadvantages with current shadow frame designs. Prior art shadow frames typically comprise clamping mechanisms that can have sharp corners. Such sharp corners can scratch or fracture substrates when brought into contact therewith such as during the loading and unloading of the substrate from the process chamber. Further, during processing, the substrate and the shadow frame experience expansion and contraction causing mechanical stress there between and often resulting in damage to the substrate. As such, the standard shadow frame may have a gap to separate it from the substrate.
When the shadow frame damages the substrate, arcing may occur. Arcing can cause damage to the susceptor, the substrate or other components of the chamber. Thus, there is a need in the art for an apparatus which prevents chipping and/or breaking of a substrate while simultaneously preventing arcing during processing.